11da177e4SLinus Torvalds /* -*- linux-c -*- --------------------------------------------------------- * 21da177e4SLinus Torvalds * 31da177e4SLinus Torvalds * linux/fs/devpts/inode.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * This file is part of the Linux kernel and is made available under 81da177e4SLinus Torvalds * the terms of the GNU General Public License, version 2, or at your 91da177e4SLinus Torvalds * option, any later version, incorporated herein by reference. 101da177e4SLinus Torvalds * 111da177e4SLinus Torvalds * ------------------------------------------------------------------------- */ 121da177e4SLinus Torvalds 1304541a2fSFabian Frederick #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 1404541a2fSFabian Frederick 151da177e4SLinus Torvalds #include <linux/module.h> 161da177e4SLinus Torvalds #include <linux/init.h> 171da177e4SLinus Torvalds #include <linux/fs.h> 181da177e4SLinus Torvalds #include <linux/sched.h> 191da177e4SLinus Torvalds #include <linux/namei.h> 205a0e3ad6STejun Heo #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/mount.h> 221da177e4SLinus Torvalds #include <linux/tty.h> 23718a9163SSukadev Bhattiprolu #include <linux/mutex.h> 241fd7317dSNick Black #include <linux/magic.h> 25718a9163SSukadev Bhattiprolu #include <linux/idr.h> 261da177e4SLinus Torvalds #include <linux/devpts_fs.h> 277a673c6bSDomen Puncer #include <linux/parser.h> 283972b7f6SFlorin Malita #include <linux/fsnotify.h> 29b87a267eSMiklos Szeredi #include <linux/seq_file.h> 301da177e4SLinus Torvalds 31b87a267eSMiklos Szeredi #define DEVPTS_DEFAULT_MODE 0600 321f8f1e29SSukadev Bhattiprolu /* 331f8f1e29SSukadev Bhattiprolu * ptmx is a new node in /dev/pts and will be unused in legacy (single- 341f8f1e29SSukadev Bhattiprolu * instance) mode. To prevent surprises in user space, set permissions of 351f8f1e29SSukadev Bhattiprolu * ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful 361f8f1e29SSukadev Bhattiprolu * permissions. 371f8f1e29SSukadev Bhattiprolu */ 381f8f1e29SSukadev Bhattiprolu #define DEVPTS_DEFAULT_PTMX_MODE 0000 39527b3e47SSukadev Bhattiprolu #define PTMX_MINOR 2 40b87a267eSMiklos Szeredi 41a4834c10SKonstantin Khlebnikov /* 42a4834c10SKonstantin Khlebnikov * sysctl support for setting limits on the number of Unix98 ptys allocated. 43a4834c10SKonstantin Khlebnikov * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly. 44a4834c10SKonstantin Khlebnikov */ 45a4834c10SKonstantin Khlebnikov static int pty_limit = NR_UNIX98_PTY_DEFAULT; 46e9aba515SKonstantin Khlebnikov static int pty_reserve = NR_UNIX98_PTY_RESERVE; 47a4834c10SKonstantin Khlebnikov static int pty_limit_min; 48e9aba515SKonstantin Khlebnikov static int pty_limit_max = INT_MAX; 49a4834c10SKonstantin Khlebnikov static int pty_count; 50a4834c10SKonstantin Khlebnikov 51a4834c10SKonstantin Khlebnikov static struct ctl_table pty_table[] = { 52a4834c10SKonstantin Khlebnikov { 53a4834c10SKonstantin Khlebnikov .procname = "max", 54a4834c10SKonstantin Khlebnikov .maxlen = sizeof(int), 55a4834c10SKonstantin Khlebnikov .mode = 0644, 56a4834c10SKonstantin Khlebnikov .data = &pty_limit, 57a4834c10SKonstantin Khlebnikov .proc_handler = proc_dointvec_minmax, 58a4834c10SKonstantin Khlebnikov .extra1 = &pty_limit_min, 59a4834c10SKonstantin Khlebnikov .extra2 = &pty_limit_max, 60a4834c10SKonstantin Khlebnikov }, { 61e9aba515SKonstantin Khlebnikov .procname = "reserve", 62e9aba515SKonstantin Khlebnikov .maxlen = sizeof(int), 63e9aba515SKonstantin Khlebnikov .mode = 0644, 64e9aba515SKonstantin Khlebnikov .data = &pty_reserve, 65e9aba515SKonstantin Khlebnikov .proc_handler = proc_dointvec_minmax, 66e9aba515SKonstantin Khlebnikov .extra1 = &pty_limit_min, 67e9aba515SKonstantin Khlebnikov .extra2 = &pty_limit_max, 68e9aba515SKonstantin Khlebnikov }, { 69a4834c10SKonstantin Khlebnikov .procname = "nr", 70a4834c10SKonstantin Khlebnikov .maxlen = sizeof(int), 71a4834c10SKonstantin Khlebnikov .mode = 0444, 72a4834c10SKonstantin Khlebnikov .data = &pty_count, 73a4834c10SKonstantin Khlebnikov .proc_handler = proc_dointvec, 74a4834c10SKonstantin Khlebnikov }, 75a4834c10SKonstantin Khlebnikov {} 76a4834c10SKonstantin Khlebnikov }; 77a4834c10SKonstantin Khlebnikov 78a4834c10SKonstantin Khlebnikov static struct ctl_table pty_kern_table[] = { 79a4834c10SKonstantin Khlebnikov { 80a4834c10SKonstantin Khlebnikov .procname = "pty", 81a4834c10SKonstantin Khlebnikov .mode = 0555, 82a4834c10SKonstantin Khlebnikov .child = pty_table, 83a4834c10SKonstantin Khlebnikov }, 84a4834c10SKonstantin Khlebnikov {} 85a4834c10SKonstantin Khlebnikov }; 86a4834c10SKonstantin Khlebnikov 87a4834c10SKonstantin Khlebnikov static struct ctl_table pty_root_table[] = { 88a4834c10SKonstantin Khlebnikov { 89a4834c10SKonstantin Khlebnikov .procname = "kernel", 90a4834c10SKonstantin Khlebnikov .mode = 0555, 91a4834c10SKonstantin Khlebnikov .child = pty_kern_table, 92a4834c10SKonstantin Khlebnikov }, 93a4834c10SKonstantin Khlebnikov {} 94a4834c10SKonstantin Khlebnikov }; 95a4834c10SKonstantin Khlebnikov 96718a9163SSukadev Bhattiprolu static DEFINE_MUTEX(allocated_ptys_lock); 97718a9163SSukadev Bhattiprolu 9831af0abbSSukadev Bhattiprolu struct pts_mount_opts { 991da177e4SLinus Torvalds int setuid; 1001da177e4SLinus Torvalds int setgid; 101f04c6ce2SEric W. Biederman kuid_t uid; 102f04c6ce2SEric W. Biederman kgid_t gid; 1031da177e4SLinus Torvalds umode_t mode; 1041f8f1e29SSukadev Bhattiprolu umode_t ptmxmode; 105eedf265aSEric W. Biederman int reserve; 106e9aba515SKonstantin Khlebnikov int max; 10731af0abbSSukadev Bhattiprolu }; 1081da177e4SLinus Torvalds 1097a673c6bSDomen Puncer enum { 110e9aba515SKonstantin Khlebnikov Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance, Opt_max, 1117a673c6bSDomen Puncer Opt_err 1127a673c6bSDomen Puncer }; 1137a673c6bSDomen Puncer 114a447c093SSteven Whitehouse static const match_table_t tokens = { 1157a673c6bSDomen Puncer {Opt_uid, "uid=%u"}, 1167a673c6bSDomen Puncer {Opt_gid, "gid=%u"}, 1177a673c6bSDomen Puncer {Opt_mode, "mode=%o"}, 1181f8f1e29SSukadev Bhattiprolu {Opt_ptmxmode, "ptmxmode=%o"}, 1192a1b2dc0SSukadev Bhattiprolu {Opt_newinstance, "newinstance"}, 120e9aba515SKonstantin Khlebnikov {Opt_max, "max=%d"}, 1217a673c6bSDomen Puncer {Opt_err, NULL} 1227a673c6bSDomen Puncer }; 1237a673c6bSDomen Puncer 124e76b7c01SSukadev Bhattiprolu struct pts_fs_info { 125e76b7c01SSukadev Bhattiprolu struct ida allocated_ptys; 12631af0abbSSukadev Bhattiprolu struct pts_mount_opts mount_opts; 12767245ff3SLinus Torvalds struct super_block *sb; 1281f8f1e29SSukadev Bhattiprolu struct dentry *ptmx_dentry; 129e76b7c01SSukadev Bhattiprolu }; 130e76b7c01SSukadev Bhattiprolu 131e76b7c01SSukadev Bhattiprolu static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) 132e76b7c01SSukadev Bhattiprolu { 133e76b7c01SSukadev Bhattiprolu return sb->s_fs_info; 134e76b7c01SSukadev Bhattiprolu } 135e76b7c01SSukadev Bhattiprolu 136eedf265aSEric W. Biederman struct pts_fs_info *devpts_acquire(struct file *filp) 13759e55e6cSSukadev Bhattiprolu { 138eedf265aSEric W. Biederman struct pts_fs_info *result; 139eedf265aSEric W. Biederman struct path path; 140eedf265aSEric W. Biederman struct super_block *sb; 141eedf265aSEric W. Biederman int err; 142eedf265aSEric W. Biederman 143eedf265aSEric W. Biederman path = filp->f_path; 144eedf265aSEric W. Biederman path_get(&path); 145eedf265aSEric W. Biederman 146eedf265aSEric W. Biederman /* Has the devpts filesystem already been found? */ 147eedf265aSEric W. Biederman sb = path.mnt->mnt_sb; 148eedf265aSEric W. Biederman if (sb->s_magic != DEVPTS_SUPER_MAGIC) { 149eedf265aSEric W. Biederman /* Is a devpts filesystem at "pts" in the same directory? */ 150eedf265aSEric W. Biederman err = path_pts(&path); 151eedf265aSEric W. Biederman if (err) { 152eedf265aSEric W. Biederman result = ERR_PTR(err); 153eedf265aSEric W. Biederman goto out; 154eedf265aSEric W. Biederman } 155eedf265aSEric W. Biederman 156eedf265aSEric W. Biederman /* Is the path the root of a devpts filesystem? */ 157eedf265aSEric W. Biederman result = ERR_PTR(-ENODEV); 158eedf265aSEric W. Biederman sb = path.mnt->mnt_sb; 159eedf265aSEric W. Biederman if ((sb->s_magic != DEVPTS_SUPER_MAGIC) || 160eedf265aSEric W. Biederman (path.mnt->mnt_root != sb->s_root)) 161eedf265aSEric W. Biederman goto out; 162eedf265aSEric W. Biederman } 163eedf265aSEric W. Biederman 164eedf265aSEric W. Biederman /* 165eedf265aSEric W. Biederman * pty code needs to hold extra references in case of last /dev/tty close 166eedf265aSEric W. Biederman */ 167eedf265aSEric W. Biederman atomic_inc(&sb->s_active); 168eedf265aSEric W. Biederman result = DEVPTS_SB(sb); 169eedf265aSEric W. Biederman 170eedf265aSEric W. Biederman out: 171eedf265aSEric W. Biederman path_put(&path); 172eedf265aSEric W. Biederman return result; 173eedf265aSEric W. Biederman } 174eedf265aSEric W. Biederman 175eedf265aSEric W. Biederman void devpts_release(struct pts_fs_info *fsi) 176eedf265aSEric W. Biederman { 177eedf265aSEric W. Biederman deactivate_super(fsi->sb); 17859e55e6cSSukadev Bhattiprolu } 17959e55e6cSSukadev Bhattiprolu 1802a1b2dc0SSukadev Bhattiprolu #define PARSE_MOUNT 0 1812a1b2dc0SSukadev Bhattiprolu #define PARSE_REMOUNT 1 1822a1b2dc0SSukadev Bhattiprolu 1831f71ebedSSukadev Bhattiprolu /* 1841f71ebedSSukadev Bhattiprolu * parse_mount_options(): 1851f71ebedSSukadev Bhattiprolu * Set @opts to mount options specified in @data. If an option is not 186eedf265aSEric W. Biederman * specified in @data, set it to its default value. 1871f71ebedSSukadev Bhattiprolu * 1881f71ebedSSukadev Bhattiprolu * Note: @data may be NULL (in which case all options are set to default). 1891f71ebedSSukadev Bhattiprolu */ 1902a1b2dc0SSukadev Bhattiprolu static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) 1911da177e4SLinus Torvalds { 1927a673c6bSDomen Puncer char *p; 193f04c6ce2SEric W. Biederman kuid_t uid; 194f04c6ce2SEric W. Biederman kgid_t gid; 1951da177e4SLinus Torvalds 19631af0abbSSukadev Bhattiprolu opts->setuid = 0; 19731af0abbSSukadev Bhattiprolu opts->setgid = 0; 198f04c6ce2SEric W. Biederman opts->uid = GLOBAL_ROOT_UID; 199f04c6ce2SEric W. Biederman opts->gid = GLOBAL_ROOT_GID; 20031af0abbSSukadev Bhattiprolu opts->mode = DEVPTS_DEFAULT_MODE; 2011f8f1e29SSukadev Bhattiprolu opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 202e9aba515SKonstantin Khlebnikov opts->max = NR_UNIX98_PTY_MAX; 2037a673c6bSDomen Puncer 204eedf265aSEric W. Biederman /* Only allow instances mounted from the initial mount 205eedf265aSEric W. Biederman * namespace to tap the reserve pool of ptys. 206eedf265aSEric W. Biederman */ 2072a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 208eedf265aSEric W. Biederman opts->reserve = 209eedf265aSEric W. Biederman (current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns); 2102a1b2dc0SSukadev Bhattiprolu 2117a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 2127a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 2137a673c6bSDomen Puncer int token; 2147a673c6bSDomen Puncer int option; 2157a673c6bSDomen Puncer 2167a673c6bSDomen Puncer if (!*p) 2171da177e4SLinus Torvalds continue; 2187a673c6bSDomen Puncer 2197a673c6bSDomen Puncer token = match_token(p, tokens, args); 2207a673c6bSDomen Puncer switch (token) { 2217a673c6bSDomen Puncer case Opt_uid: 2227a673c6bSDomen Puncer if (match_int(&args[0], &option)) 2237a673c6bSDomen Puncer return -EINVAL; 224f04c6ce2SEric W. Biederman uid = make_kuid(current_user_ns(), option); 225f04c6ce2SEric W. Biederman if (!uid_valid(uid)) 226f04c6ce2SEric W. Biederman return -EINVAL; 227f04c6ce2SEric W. Biederman opts->uid = uid; 22831af0abbSSukadev Bhattiprolu opts->setuid = 1; 2297a673c6bSDomen Puncer break; 2307a673c6bSDomen Puncer case Opt_gid: 2317a673c6bSDomen Puncer if (match_int(&args[0], &option)) 2327a673c6bSDomen Puncer return -EINVAL; 233f04c6ce2SEric W. Biederman gid = make_kgid(current_user_ns(), option); 234f04c6ce2SEric W. Biederman if (!gid_valid(gid)) 235f04c6ce2SEric W. Biederman return -EINVAL; 236f04c6ce2SEric W. Biederman opts->gid = gid; 23731af0abbSSukadev Bhattiprolu opts->setgid = 1; 2387a673c6bSDomen Puncer break; 2397a673c6bSDomen Puncer case Opt_mode: 2407a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 2417a673c6bSDomen Puncer return -EINVAL; 24231af0abbSSukadev Bhattiprolu opts->mode = option & S_IALLUGO; 2437a673c6bSDomen Puncer break; 2441f8f1e29SSukadev Bhattiprolu case Opt_ptmxmode: 2451f8f1e29SSukadev Bhattiprolu if (match_octal(&args[0], &option)) 2461f8f1e29SSukadev Bhattiprolu return -EINVAL; 2471f8f1e29SSukadev Bhattiprolu opts->ptmxmode = option & S_IALLUGO; 2481f8f1e29SSukadev Bhattiprolu break; 2492a1b2dc0SSukadev Bhattiprolu case Opt_newinstance: 2502a1b2dc0SSukadev Bhattiprolu break; 251e9aba515SKonstantin Khlebnikov case Opt_max: 252e9aba515SKonstantin Khlebnikov if (match_int(&args[0], &option) || 253e9aba515SKonstantin Khlebnikov option < 0 || option > NR_UNIX98_PTY_MAX) 254e9aba515SKonstantin Khlebnikov return -EINVAL; 255e9aba515SKonstantin Khlebnikov opts->max = option; 256e9aba515SKonstantin Khlebnikov break; 2577a673c6bSDomen Puncer default: 25804541a2fSFabian Frederick pr_err("called with bogus options\n"); 2591da177e4SLinus Torvalds return -EINVAL; 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds } 2621da177e4SLinus Torvalds 2631da177e4SLinus Torvalds return 0; 2641da177e4SLinus Torvalds } 2651da177e4SLinus Torvalds 2661f8f1e29SSukadev Bhattiprolu static int mknod_ptmx(struct super_block *sb) 26753af8ee4SSukadev Bhattiprolu { 2681f8f1e29SSukadev Bhattiprolu int mode; 2691f8f1e29SSukadev Bhattiprolu int rc = -ENOMEM; 2701f8f1e29SSukadev Bhattiprolu struct dentry *dentry; 2711f8f1e29SSukadev Bhattiprolu struct inode *inode; 2721f8f1e29SSukadev Bhattiprolu struct dentry *root = sb->s_root; 27353af8ee4SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 27453af8ee4SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 275ec2aa8e8SEric W. Biederman kuid_t root_uid; 276ec2aa8e8SEric W. Biederman kgid_t root_gid; 277ec2aa8e8SEric W. Biederman 278ec2aa8e8SEric W. Biederman root_uid = make_kuid(current_user_ns(), 0); 279ec2aa8e8SEric W. Biederman root_gid = make_kgid(current_user_ns(), 0); 280ec2aa8e8SEric W. Biederman if (!uid_valid(root_uid) || !gid_valid(root_gid)) 281ec2aa8e8SEric W. Biederman return -EINVAL; 28253af8ee4SSukadev Bhattiprolu 2835955102cSAl Viro inode_lock(d_inode(root)); 2841f8f1e29SSukadev Bhattiprolu 2851f8f1e29SSukadev Bhattiprolu /* If we have already created ptmx node, return */ 2861f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 2871f8f1e29SSukadev Bhattiprolu rc = 0; 2881f8f1e29SSukadev Bhattiprolu goto out; 2891f8f1e29SSukadev Bhattiprolu } 2901f8f1e29SSukadev Bhattiprolu 2911f8f1e29SSukadev Bhattiprolu dentry = d_alloc_name(root, "ptmx"); 2921f8f1e29SSukadev Bhattiprolu if (!dentry) { 29304541a2fSFabian Frederick pr_err("Unable to alloc dentry for ptmx node\n"); 2941f8f1e29SSukadev Bhattiprolu goto out; 2951f8f1e29SSukadev Bhattiprolu } 2961f8f1e29SSukadev Bhattiprolu 2971f8f1e29SSukadev Bhattiprolu /* 2981f8f1e29SSukadev Bhattiprolu * Create a new 'ptmx' node in this mount of devpts. 2991f8f1e29SSukadev Bhattiprolu */ 3001f8f1e29SSukadev Bhattiprolu inode = new_inode(sb); 3011f8f1e29SSukadev Bhattiprolu if (!inode) { 30204541a2fSFabian Frederick pr_err("Unable to alloc inode for ptmx node\n"); 3031f8f1e29SSukadev Bhattiprolu dput(dentry); 3041f8f1e29SSukadev Bhattiprolu goto out; 3051f8f1e29SSukadev Bhattiprolu } 3061f8f1e29SSukadev Bhattiprolu 3071f8f1e29SSukadev Bhattiprolu inode->i_ino = 2; 3081f8f1e29SSukadev Bhattiprolu inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 3091f8f1e29SSukadev Bhattiprolu 3101f8f1e29SSukadev Bhattiprolu mode = S_IFCHR|opts->ptmxmode; 3111f8f1e29SSukadev Bhattiprolu init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); 312ec2aa8e8SEric W. Biederman inode->i_uid = root_uid; 313ec2aa8e8SEric W. Biederman inode->i_gid = root_gid; 3141f8f1e29SSukadev Bhattiprolu 3151f8f1e29SSukadev Bhattiprolu d_add(dentry, inode); 3161f8f1e29SSukadev Bhattiprolu 3171f8f1e29SSukadev Bhattiprolu fsi->ptmx_dentry = dentry; 3181f8f1e29SSukadev Bhattiprolu rc = 0; 3191f8f1e29SSukadev Bhattiprolu out: 3205955102cSAl Viro inode_unlock(d_inode(root)); 3211f8f1e29SSukadev Bhattiprolu return rc; 3221f8f1e29SSukadev Bhattiprolu } 3231f8f1e29SSukadev Bhattiprolu 3241f8f1e29SSukadev Bhattiprolu static void update_ptmx_mode(struct pts_fs_info *fsi) 3251f8f1e29SSukadev Bhattiprolu { 3261f8f1e29SSukadev Bhattiprolu struct inode *inode; 3271f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 3282b0143b5SDavid Howells inode = d_inode(fsi->ptmx_dentry); 3291f8f1e29SSukadev Bhattiprolu inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; 3301f8f1e29SSukadev Bhattiprolu } 3311f8f1e29SSukadev Bhattiprolu } 3321f8f1e29SSukadev Bhattiprolu 3331f8f1e29SSukadev Bhattiprolu static int devpts_remount(struct super_block *sb, int *flags, char *data) 3341f8f1e29SSukadev Bhattiprolu { 3351f8f1e29SSukadev Bhattiprolu int err; 3361f8f1e29SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 3371f8f1e29SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 3381f8f1e29SSukadev Bhattiprolu 33902b9984dSTheodore Ts'o sync_filesystem(sb); 3402a1b2dc0SSukadev Bhattiprolu err = parse_mount_options(data, PARSE_REMOUNT, opts); 3411f8f1e29SSukadev Bhattiprolu 3421f8f1e29SSukadev Bhattiprolu /* 3431f8f1e29SSukadev Bhattiprolu * parse_mount_options() restores options to default values 3441f8f1e29SSukadev Bhattiprolu * before parsing and may have changed ptmxmode. So, update the 3451f8f1e29SSukadev Bhattiprolu * mode in the inode too. Bogus options don't fail the remount, 3461f8f1e29SSukadev Bhattiprolu * so do this even on error return. 3471f8f1e29SSukadev Bhattiprolu */ 3481f8f1e29SSukadev Bhattiprolu update_ptmx_mode(fsi); 3491f8f1e29SSukadev Bhattiprolu 3501f8f1e29SSukadev Bhattiprolu return err; 35153af8ee4SSukadev Bhattiprolu } 35253af8ee4SSukadev Bhattiprolu 35334c80b1dSAl Viro static int devpts_show_options(struct seq_file *seq, struct dentry *root) 354b87a267eSMiklos Szeredi { 35534c80b1dSAl Viro struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); 35631af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 35731af0abbSSukadev Bhattiprolu 35831af0abbSSukadev Bhattiprolu if (opts->setuid) 35904541a2fSFabian Frederick seq_printf(seq, ",uid=%u", 36004541a2fSFabian Frederick from_kuid_munged(&init_user_ns, opts->uid)); 36131af0abbSSukadev Bhattiprolu if (opts->setgid) 36204541a2fSFabian Frederick seq_printf(seq, ",gid=%u", 36304541a2fSFabian Frederick from_kgid_munged(&init_user_ns, opts->gid)); 36431af0abbSSukadev Bhattiprolu seq_printf(seq, ",mode=%03o", opts->mode); 3651f8f1e29SSukadev Bhattiprolu seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); 366e9aba515SKonstantin Khlebnikov if (opts->max < NR_UNIX98_PTY_MAX) 367e9aba515SKonstantin Khlebnikov seq_printf(seq, ",max=%d", opts->max); 368b87a267eSMiklos Szeredi 369b87a267eSMiklos Szeredi return 0; 370b87a267eSMiklos Szeredi } 371b87a267eSMiklos Szeredi 372ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 3731da177e4SLinus Torvalds .statfs = simple_statfs, 3741da177e4SLinus Torvalds .remount_fs = devpts_remount, 375b87a267eSMiklos Szeredi .show_options = devpts_show_options, 3761da177e4SLinus Torvalds }; 3771da177e4SLinus Torvalds 37867245ff3SLinus Torvalds static void *new_pts_fs_info(struct super_block *sb) 379e76b7c01SSukadev Bhattiprolu { 380e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi; 381e76b7c01SSukadev Bhattiprolu 382e76b7c01SSukadev Bhattiprolu fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); 383e76b7c01SSukadev Bhattiprolu if (!fsi) 384e76b7c01SSukadev Bhattiprolu return NULL; 385e76b7c01SSukadev Bhattiprolu 386e76b7c01SSukadev Bhattiprolu ida_init(&fsi->allocated_ptys); 38731af0abbSSukadev Bhattiprolu fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; 3881f8f1e29SSukadev Bhattiprolu fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 38967245ff3SLinus Torvalds fsi->sb = sb; 390e76b7c01SSukadev Bhattiprolu 391e76b7c01SSukadev Bhattiprolu return fsi; 392e76b7c01SSukadev Bhattiprolu } 393e76b7c01SSukadev Bhattiprolu 3941da177e4SLinus Torvalds static int 3951da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 3961da177e4SLinus Torvalds { 3971da177e4SLinus Torvalds struct inode *inode; 398dee87d47SEric W. Biederman int error; 3991da177e4SLinus Torvalds 400cc50a07aSEric W. Biederman s->s_iflags &= ~SB_I_NODEV; 4011da177e4SLinus Torvalds s->s_blocksize = 1024; 4021da177e4SLinus Torvalds s->s_blocksize_bits = 10; 4031da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 4041da177e4SLinus Torvalds s->s_op = &devpts_sops; 4051da177e4SLinus Torvalds s->s_time_gran = 1; 4061da177e4SLinus Torvalds 407dee87d47SEric W. Biederman error = -ENOMEM; 40867245ff3SLinus Torvalds s->s_fs_info = new_pts_fs_info(s); 409e76b7c01SSukadev Bhattiprolu if (!s->s_fs_info) 410e76b7c01SSukadev Bhattiprolu goto fail; 411e76b7c01SSukadev Bhattiprolu 412dee87d47SEric W. Biederman error = parse_mount_options(data, PARSE_MOUNT, &DEVPTS_SB(s)->mount_opts); 413dee87d47SEric W. Biederman if (error) 414dee87d47SEric W. Biederman goto fail; 415dee87d47SEric W. Biederman 416dee87d47SEric W. Biederman error = -ENOMEM; 4171da177e4SLinus Torvalds inode = new_inode(s); 4181da177e4SLinus Torvalds if (!inode) 4193850aba7SAl Viro goto fail; 4201da177e4SLinus Torvalds inode->i_ino = 1; 4211da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 4221da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 4231da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 4241da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 425bfe86848SMiklos Szeredi set_nlink(inode, 2); 4261da177e4SLinus Torvalds 42748fde701SAl Viro s->s_root = d_make_root(inode); 428180d9044SEric W. Biederman if (!s->s_root) { 42904541a2fSFabian Frederick pr_err("get root dentry failed\n"); 430180d9044SEric W. Biederman goto fail; 431180d9044SEric W. Biederman } 432e76b7c01SSukadev Bhattiprolu 433180d9044SEric W. Biederman error = mknod_ptmx(s); 434180d9044SEric W. Biederman if (error) 435180d9044SEric W. Biederman goto fail_dput; 436180d9044SEric W. Biederman 437180d9044SEric W. Biederman return 0; 438180d9044SEric W. Biederman fail_dput: 439180d9044SEric W. Biederman dput(s->s_root); 440180d9044SEric W. Biederman s->s_root = NULL; 4411da177e4SLinus Torvalds fail: 442dee87d47SEric W. Biederman return error; 4431da177e4SLinus Torvalds } 4441da177e4SLinus Torvalds 4452a1b2dc0SSukadev Bhattiprolu /* 446fc14f2feSAl Viro * devpts_mount() 447289f00e2SSukadev Bhattiprolu * 448eedf265aSEric W. Biederman * Mount a new (private) instance of devpts. PTYs created in this 449eedf265aSEric W. Biederman * instance are independent of the PTYs in other devpts instances. 450d4076ac5SSukadev Bhattiprolu */ 451fc14f2feSAl Viro static struct dentry *devpts_mount(struct file_system_type *fs_type, 452fc14f2feSAl Viro int flags, const char *dev_name, void *data) 4531da177e4SLinus Torvalds { 454c1b241f0SEric W. Biederman return mount_nodev(fs_type, flags, data, devpts_fill_super); 455482984f0SSukadev Bhattiprolu } 456482984f0SSukadev Bhattiprolu 457e76b7c01SSukadev Bhattiprolu static void devpts_kill_sb(struct super_block *sb) 458e76b7c01SSukadev Bhattiprolu { 459e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 460e76b7c01SSukadev Bhattiprolu 46140b320e1SEric W. Biederman if (fsi) 46266da0e1fSIlija Hadzic ida_destroy(&fsi->allocated_ptys); 463e76b7c01SSukadev Bhattiprolu kfree(fsi); 4641f8f1e29SSukadev Bhattiprolu kill_litter_super(sb); 465e76b7c01SSukadev Bhattiprolu } 466e76b7c01SSukadev Bhattiprolu 4671da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 4681da177e4SLinus Torvalds .name = "devpts", 469fc14f2feSAl Viro .mount = devpts_mount, 470e76b7c01SSukadev Bhattiprolu .kill_sb = devpts_kill_sb, 471cc50a07aSEric W. Biederman .fs_flags = FS_USERNS_MOUNT, 4721da177e4SLinus Torvalds }; 4731da177e4SLinus Torvalds 4741da177e4SLinus Torvalds /* 4751da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 4761da177e4SLinus Torvalds * to the System V naming convention 4771da177e4SLinus Torvalds */ 4781da177e4SLinus Torvalds 47967245ff3SLinus Torvalds int devpts_new_index(struct pts_fs_info *fsi) 480718a9163SSukadev Bhattiprolu { 481718a9163SSukadev Bhattiprolu int index; 4827ee7c12bSAlexey Dobriyan int ida_ret; 483718a9163SSukadev Bhattiprolu 484718a9163SSukadev Bhattiprolu retry: 485835aa440SAlan Cox if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) 486718a9163SSukadev Bhattiprolu return -ENOMEM; 487718a9163SSukadev Bhattiprolu 488718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 489eedf265aSEric W. Biederman if (pty_count >= (pty_limit - 490eedf265aSEric W. Biederman (fsi->mount_opts.reserve ? 0 : pty_reserve))) { 491e9aba515SKonstantin Khlebnikov mutex_unlock(&allocated_ptys_lock); 492e9aba515SKonstantin Khlebnikov return -ENOSPC; 493e9aba515SKonstantin Khlebnikov } 494e9aba515SKonstantin Khlebnikov 495e76b7c01SSukadev Bhattiprolu ida_ret = ida_get_new(&fsi->allocated_ptys, &index); 4967ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 497718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 4987ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 499718a9163SSukadev Bhattiprolu goto retry; 500718a9163SSukadev Bhattiprolu return -EIO; 501718a9163SSukadev Bhattiprolu } 502718a9163SSukadev Bhattiprolu 503e9aba515SKonstantin Khlebnikov if (index >= fsi->mount_opts.max) { 504e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, index); 505718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 506e9aba515SKonstantin Khlebnikov return -ENOSPC; 507718a9163SSukadev Bhattiprolu } 508a4834c10SKonstantin Khlebnikov pty_count++; 509718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 510718a9163SSukadev Bhattiprolu return index; 511718a9163SSukadev Bhattiprolu } 512718a9163SSukadev Bhattiprolu 51367245ff3SLinus Torvalds void devpts_kill_index(struct pts_fs_info *fsi, int idx) 514718a9163SSukadev Bhattiprolu { 515718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 516e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, idx); 517a4834c10SKonstantin Khlebnikov pty_count--; 518718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 519718a9163SSukadev Bhattiprolu } 520718a9163SSukadev Bhattiprolu 5211dcb8e6dSJiri Slaby /** 5221dcb8e6dSJiri Slaby * devpts_pty_new -- create a new inode in /dev/pts/ 5231dcb8e6dSJiri Slaby * @ptmx_inode: inode of the master 5241dcb8e6dSJiri Slaby * @device: major+minor of the node to be created 5251dcb8e6dSJiri Slaby * @index: used as a name of the node 5261dcb8e6dSJiri Slaby * @priv: what's given back by devpts_get_priv 5271dcb8e6dSJiri Slaby * 5281dcb8e6dSJiri Slaby * The created inode is returned. Remove it from /dev/pts/ by devpts_pty_kill. 5291dcb8e6dSJiri Slaby */ 5308ead9dd5SLinus Torvalds struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv) 5311da177e4SLinus Torvalds { 5321da177e4SLinus Torvalds struct dentry *dentry; 533eedf265aSEric W. Biederman struct super_block *sb = fsi->sb; 534162b97cfSJiri Slaby struct inode *inode; 5359ce71148SJosh Triplett struct dentry *root; 5369ce71148SJosh Triplett struct pts_mount_opts *opts; 53789a52e10SSukadev Bhattiprolu char s[12]; 5381da177e4SLinus Torvalds 5399ce71148SJosh Triplett root = sb->s_root; 5409ce71148SJosh Triplett opts = &fsi->mount_opts; 5419ce71148SJosh Triplett 542162b97cfSJiri Slaby inode = new_inode(sb); 5431da177e4SLinus Torvalds if (!inode) 544162b97cfSJiri Slaby return ERR_PTR(-ENOMEM); 5451da177e4SLinus Torvalds 546f11afb61SJiri Slaby inode->i_ino = index + 3; 547d0eafc7dSDavid Howells inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); 548d0eafc7dSDavid Howells inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); 5491da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 5508ead9dd5SLinus Torvalds init_special_inode(inode, S_IFCHR|opts->mode, MKDEV(UNIX98_PTY_SLAVE_MAJOR, index)); 5511da177e4SLinus Torvalds 552f11afb61SJiri Slaby sprintf(s, "%d", index); 55389a52e10SSukadev Bhattiprolu 55459e55e6cSSukadev Bhattiprolu dentry = d_alloc_name(root, s); 555b12d1259SAndrey Vagin if (dentry) { 5568ead9dd5SLinus Torvalds dentry->d_fsdata = priv; 55789a52e10SSukadev Bhattiprolu d_add(dentry, inode); 5582b0143b5SDavid Howells fsnotify_create(d_inode(root), dentry); 559aa597bc1SAndrey Vagin } else { 560aa597bc1SAndrey Vagin iput(inode); 5618ead9dd5SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 5623972b7f6SFlorin Malita } 5631da177e4SLinus Torvalds 5648ead9dd5SLinus Torvalds return dentry; 5651da177e4SLinus Torvalds } 5661da177e4SLinus Torvalds 5671dcb8e6dSJiri Slaby /** 5681dcb8e6dSJiri Slaby * devpts_get_priv -- get private data for a slave 5691dcb8e6dSJiri Slaby * @pts_inode: inode of the slave 5701dcb8e6dSJiri Slaby * 5711dcb8e6dSJiri Slaby * Returns whatever was passed as priv in devpts_pty_new for a given inode. 5721dcb8e6dSJiri Slaby */ 5738ead9dd5SLinus Torvalds void *devpts_get_priv(struct dentry *dentry) 5741da177e4SLinus Torvalds { 5753e423945SLinus Torvalds if (dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC) 5763e423945SLinus Torvalds return NULL; 5778ead9dd5SLinus Torvalds return dentry->d_fsdata; 5781da177e4SLinus Torvalds } 5791da177e4SLinus Torvalds 5801dcb8e6dSJiri Slaby /** 5811dcb8e6dSJiri Slaby * devpts_pty_kill -- remove inode form /dev/pts/ 5821dcb8e6dSJiri Slaby * @inode: inode of the slave to be removed 5831dcb8e6dSJiri Slaby * 5841dcb8e6dSJiri Slaby * This is an inverse operation of devpts_pty_new. 5851dcb8e6dSJiri Slaby */ 5868ead9dd5SLinus Torvalds void devpts_pty_kill(struct dentry *dentry) 5871da177e4SLinus Torvalds { 5888ead9dd5SLinus Torvalds WARN_ON_ONCE(dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC); 5891da177e4SLinus Torvalds 5908ead9dd5SLinus Torvalds dentry->d_fsdata = NULL; 5918ead9dd5SLinus Torvalds drop_nlink(dentry->d_inode); 5921da177e4SLinus Torvalds d_delete(dentry); 593835aa440SAlan Cox dput(dentry); /* d_alloc_name() in devpts_pty_new() */ 5941da177e4SLinus Torvalds } 5951da177e4SLinus Torvalds 5961da177e4SLinus Torvalds static int __init init_devpts_fs(void) 5971da177e4SLinus Torvalds { 5981da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 5991da177e4SLinus Torvalds if (!err) { 600eedf265aSEric W. Biederman register_sysctl_table(pty_root_table); 6011da177e4SLinus Torvalds } 6021da177e4SLinus Torvalds return err; 6031da177e4SLinus Torvalds } 6041da177e4SLinus Torvalds module_init(init_devpts_fs) 605